The objective of this project is to study the control mechanisms for protein accumulation during the aging process. In vivo rates of synthesis and degradation of total proteins (protein turnover) will be determined in free-living nematodes (Turbatrix aceti) as a function of age. Immunological techniques will also be employed to determine synthetic and degradative rates of individual enzymes known to undergo age-related modifications in T. aceti. The work will further determine if changes in protein turnover occur with age in Fischer 344 rats. Double isotope and immunological procedures will be used to examine rates of synthesis and degradation of protein in selected tissues, and of specific proteins in these tissues, throughout the lifespan of the animal. The relationship of altered turnover rates (if found) to the appearance of altered enzymes in old organizms will be explored.